This invention relates to the production of aluminum chloride of a purity suitable for subsequent electrolytic reduction to metallic aluminum. More particularly, this invention relates to the cooling of aluminum chloride vapors produced during the chlorination of aluminous material to produce high-purity aluminum chloride.
The process of producing aluminum chloride by chlorination of an aluminous material, such as aluminum oxide, as described and claimed in King et al U.S. Pat. No. 3,786,135, involves the filtration of the gaseous effluent emanating from the chlorination vessel. These vapors include aluminum chloride vapors and may, initially, be at temperatures as high as 600.degree.-800.degree. C. Such temperatures are much too high for the filtration equipment which must be used to remove impurities such as entrained solids from the gases. It is therefore necessary to cool the gases down to a temperature which can be successfully withstood by the filtration equipment.
In the aforesaid King et al. patent the vapors are shown as passing through a cooler having a jacket through which a suitable coolant is flowed. While this has been found to be satisfactory, it does involve regulation of the cooling to avoid plugging of the cooler and requires use of additional energy and resultant expense in providing the coolant for this cooler.